The breeding habit of the Japanese harvest mouse, Micromys japonicus Thomas I. Parturition period and litter size Satoshi Shiraishi

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1 九州大学学術情報リポジトリ Kyushu University Institutional Repository カヤネズミの繁殖習性 I : 出産期と産仔数白石, 哲九州大学農学部動物学教室 Shiraishi, Satoshi Zoological Lavoratory, Faculty of Agriculture, Kyushu University 出版情報 : 九州大學農學部學藝雜誌. 20 (1), pp.87-94, 九州大學農學部バージョン :published 権利関係 :

2 The breeding habit of the Japanese harvest mouse, Micromys japonicus Thomas I. Parturition period and litter size Satoshi Shiraishi

3 Fig. 1. Northern part of Kurume City, especially showing the place where this study was carried out. CR: Chikugo River, F : Fuchinoue, H : Higashi-Kushiwara, K: Komorino, M : Miyanojin, S: Sasayama Shrine. Table 1. Meteorological statistics in Kurume City* (Long '30," Lat '30"). * Average of these 50 years.

4 Fig. 2. Diagram of temperature and rainfall in each month of the year in Kurume City (Average of these 50 years). Fig. 3. (A) : Cases of parturition in Honshu by previous some authors. Symbols are as follows : W : Watanabe (1937), F : Fujiwara (1958 and 1961), K : Kuroda (1931), Y : Yamaguchi (1936), T: Takada (?)-from N : Naora (1941), Imaizumi (1949), I : Imaizumi (1949). (B) : Number of globular nests that contained suckling and young (Shiraishi, 1962). Symbols are as follows : black column : 1957, horizontally-hatched column : 1958, dotted column : 1959, slantly-hatched column : 1960, white column : (C) : Cases of parturition at laboratory (Shiraishi, 1962). Symbols are same as (B).

5 Table 2. Collection data of litters in the nests.

6 * Collected by Mr. Junjiro Fujii. t Acquired from the stomach of a small snake which crept away from the nest of this mouse. tt Collected by Mr. Motokazu Takahashi. " Collected by Mr. Keiichi Mori. Collected by Miss Eiko Matsuo. ** Semi-mummified, so that the sexing was impossible.

7 Table 3. Collection data classified in each month of the year. The figures in parentheses show that in these cases exact litter size could not be recognized, because some of the young which consisted of each litter ran away at the collection. So that in the statistical treatment, these cases were excluded.

Fekete, E., 1947. Differences in the effect of uterine environment upon development in the dba and C-57 black strains of mice. Anat. Rec., 98(3) : 409-415. Murray, W. S., 1934.

8 Fekete, E., Differences in the effect of uterine environment upon development in the dba and C-57 black strains of mice. Anat. Rec., 98(3) : Murray, W. S., The breeding behavior of the dilute brown stock of mice (little dba). Am. J. Cancer., 20: Temminck, C. J. and Schlegel, H., Fauna japonica, 3. Mammalia, Reptilia. Lugduni Batavorum. Thomas, The Duke of Bedford's zoological exploration in Eastern Asia. I. List of mammals obtained by Mr. M. P. Anderson in Japan. Proc. Zool. Soc., 1905: Resume In the breeding season this kind of harvest mouse, Micromys japonicus Thomas, makes a globular nest just like an orange fruit with leaves of wheat (in spring), miscanthus (in late spring to early winter), rice plant (in autumn) etc. at the middle height of their stems (about 0.8 to 1.0 m high) and yields its baby young in it. The author has decided the parturition period, litter size and sex-ratio of this mouse from the result of collection of the nest, suckling and young. 'l'his study has chiefly been c arried out from May, 1957 to December, 1959 at the dry-river bed of the Chikugo which runs in the suburbs of Kurume City, Fukuoka Prefecture. The results are as follows: 1) The parturition period of this kind of mouse is divided into two periods, namely, May to

9 June and September to December under natural conditions. Among many environmental factors, temperature seems to have a close relation with the parturition period. 2) The average litter size in May to June is 4.00±0.34 (S. E.) (total number of suckling and young are 68 in 17 cases), while 6.11±0.23 (S. E.) (total number 214 in 35 cases) in September to December. As the result of statistical inspection using the confidence of intervals of the population mean (under the level of significance 1 %), significant difference has been found between these two figures. The average litter size throughout a year is 5.42±0.23 (S. E.) (total number 282 in 52 cases). 3) The sex-ratio is : a` , but it has been clarified that there is no significant difference between the number of male and female as the result of X2-test. Zoological Laboratory, Faculty of Agriculture, Kyushu University Explanation of Plate 5 Fig. 1. The well woven globular nest of the Japanese harvest mouse in the miscanthus bush (photographed on Oct. 11, 1958). Fig. 2. The young of about seven to eight days old. This litter consisted of seven young ((3,3 : Q 4) (photographed on Oct. 15, 1961). Fig. 3. The globular nest in rice field (photographed on Oct. 15, 1961). Fig. 4. The trapped harvest mouse at the entrance of winter shelter that was in the ground (photographed on Jan. 8, 1961).

11 Explanation of Plate 6 The view of the place where this study has been carried out. Fig. 1. Kurume-Ohashi and its neighboring vegetation (photographed from the upper stream on Oct. 11, 1958). Fig. 2. Komorino-Bashi and its neighboring vegetation (photographed from the upper stream on Oct. 11, 1958).

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九州大学学術情報リポジトリ Kyushu University Institutional Repository 熊本県水俣市の限界集落における耕作放棄地の拡大とその要因寺床, 幸雄九州大学大学院人文科学府 : 博士後期課程 : 農村農業地理学 Teratoko, Yukio http://hdl.handle.net/2324/20036 出版情報 : 地理学評論. 82 (6), pp.588-603,